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TOPIC: ? Get IP from remote site ?

? Get IP from remote site ? 9 years 4 months ago #21750

  • beexo
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Suppose I have a site where the router gets a dynamic IP from the ISP, and I don´t have DynDNS or any other to resolve the IP.

The question is, how can I find out at any point in time what is the IP that has been attibuted to the router by the ISP? Note: I am not at the site when trying to get the IP.


Cheers.
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Re: ? Get IP from remote site ? 9 years 4 months ago #21751

  • Smurf
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Don't think it would be possible, like you said, DynDNS would be the way to do that.
Wayne Murphy
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Now working for a Security Company called Sec-1 Ltd in the UK, for any
Penetration Testing work visit www.sec-1.com or PM me for details.
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Re: ? Get IP from remote site ? 9 years 4 months ago #21755

  • S0lo
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Do you have a static IP at your remote site ? If yes, Say it's 123.1.2.3.

Here is a very dirty way to do it. On your PC that has a dynamic IP, Run a command prompt with

[code:1]ping 123.1.2.3 -t[/code:1]

Then use a sniffer at your remote site. watch those ping packets and check thier source address.

A better way is to have an FTP server/account. And let your ISP machine sechedule a transfer of a file (say IP.txt) that contains your IP. Any time you want your IP. you could simply login to the FTP server and fetch that file.
Studying CCNP...

Ammar Muqaddas
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Re: ? Get IP from remote site ? 9 years 4 months ago #21775

  • beexo
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No static IP.

If you have dynDNS or any other service of this sort, the router must notify the service that the IP has changed. Correct? And for this to happen, the router must be configured to do so. Am I right? Or can the update be done from any computer behind the router?

Now supose there is a Dynamic DNS service attributed to this site that I do not know about. But I do have the real IP address. Is it possible to find out the dynDNS site name?
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Re: ? Get IP from remote site ? 9 years 4 months ago #21786

  • Smurf
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Hi there,

The DynDNS service works by installing a small application onto a machine within the network. It then connects to the DynDNS Servers and the servers/services are able to detect the IP Address the request is coming from and update the necessary DNS entries.

If you have the dyndns address, then you can use DNS Stuff to do a lookup on that address to find the ip address.

Unfortunately, it doesn't appear to keep a reverse lookup so you would be unable to find out the site name from the real ip address (well, the service is use doesn't)

Cheers

Wayne
Wayne Murphy
Firewall.cx Team Member
www.firewall.cx

Now working for a Security Company called Sec-1 Ltd in the UK, for any
Penetration Testing work visit www.sec-1.com or PM me for details.
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Re: ? Get IP from remote site ? 9 years 4 months ago #21880

  • beexo
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Someone has written a small program to obtain the IP attributed to the router on a client's site. The program works well. So I am thinking that he must be using some sort of Dynamic DNS service. But for sure it is not the router that calls DynDNS for an updaste of the IP. Só I am now thinking :roll: , Does DynDNS detect a change of IP automatically? Because if it does not, it must be a machine within the network comunicating with DynDNS. Or he's using some special formula.
Care to comment!
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